With the people's increasing requirements on the future communication, a cell-edge spectrum efficiency is more valued, and how to improve a cell-edge transmission quality and throughput capacity becomes a hot research topic. Antennas of multiple Access Points (AP) are adopted to transmit and receive coordinately in the Coordinated Multi-Point (CoMP) technology, one or more access points are set for one base station (cell), the multiple points of the CoMP coordination can be multiple access points from one cell or multiple access points from multiple cells, wherein, cells includes a primary cell and a coordinated cell of the terminal. A cell-edge interference problem can be effectively solved with the CoMP, which then increases a capacity and reliability of the wireless links. Therefore, the CoMP technology is introduced into a Long Term Evolution-Advanced (LTE-A) system as a key technology.
A CoMP system considers an antenna calibration problem between APs in a Time Division Duplexing (TDD) mode, respective independent antenna calibration results of the APs are: HDL=C*HUL, wherein C is a plural scalar of a downlink deviation and it includes a phase and an amplitude, HDL is a downlink channel frequency domain response, and HUL is an uplink channel frequency domain response; the antenna calibration does not influence a single AP, but uplink and downlink channel deviations C of different APs are different. Therefore, when the CoMP system has multiple APs, uplink and downlink channel parameter differences resulted from differences of plurals C will exist between different APs, including a phase difference and an amplitude difference. For example, if an uplink and downlink channel frequency domain response difference of an AP1 is C1, and an uplink and downlink channel difference of an AP2 is C2, an uplink and downlink channel parameter difference between the AP1 and the AP2 is ΔC=C1/C2. This makes the phase difference and amplitude difference exist between data in Joint Transmission (JT) of different APs, which causes that the data cannot be transmitted coherently between the APs well, thereby degrading the system performance.